Chronic kidney disease (CKD) leads to progressive loss of kidney function resulting in damaging consequences to the patient. While a role for altered oxygenation status in CKD has been postulated, there is no evidence relevant to human disease. This is due to the lack of non-invasive methods to assess renal oxygenation in vivo in humans. Also, advanced CKD is commonly associated with anemia and it is believed to be related to reduced or lack of increase in erythropoietin (EPO) production. This in turn is believed to be due to enhanced renal cortical oxygen levels. Blood oxygenation level dependent (BOLD) MRI technique as applied to intra-renal oxygenation has been shown to be sensitive in evaluating renal oxygenation both in rat and human kidneys. Currently there is no other known technique that can be used to monitor renal oxygenation status in human kidneys. Based on this background, this proposal extends the present findings in healthy and hypertensive kidneys in both animals and humans using BOLD MRI to evaluate intra-renal oxygenation in CKD patients. For the first time the technique will be extended to human subjects at different stages of disease progression. A successful outcome of this proposal would allow for the first time to appreciate that the renal oxygenation status in patients with CKD at various stages of disease progression compared to healthy controls. It would also support the use of BOLD MRI measurements as a useful non-invasive tool in the evaluation of patients with CKD. These may motivate evaluation of novel interventions specifically targeting hypoxia and hence should have significant consequences in the clinical management of CKD. PUBLIC HEALTH RELEVANCE: Over 7 million people in the US suffer from chronic kidney disease and about half a million will await kidney replacement therapy. It is believed that the oxygen availability within the kidney may be an important determinant of the progression of disease. This study will utilize a non-invasive method to study the oxygen availability within the human kidneys at various stages of disease progression. This would allow for better understanding of the disease process and in turn allow for developing preventive measures.